Pneumatic Cylinders Help Increase Palletizer Speed by 26%
by Philip Vivirito
Philip Vivirito is Industrial Distribution Manager for Parker Hannifin Corporation
Speed is critical in material-handling operations. St. Louis-based FKI Logistex, a leading supplier of palletizers and depalletizers to the material handling industry, needed to increase speed rates on the case turner component of some of its palletizer products in response to customer specifications.
These high-speed case palletizers operate in warehouse and distribution, manufacturing, airports, and postal and parcel applications. The A-940 inline palletizer can reach speeds in excess of 200 cases
per minute. To meet customer demands for faster palletizing speeds, FKI Logistex explored a prototype pneumatic cylinder, the P5L, from Parker Hannifin.
Each palletizer has three to four case turners, which are vertically mounted guided cylinders with an
attached plate that strokes out and turns oncoming cases for stacking in intricate patterns on the pallets.
If one of the cylinders is too slow, it slows the entire stacking operation.
Company engineers contacted Parker Hannifin for a pneumatic answer to the production speed issues
identified by customers, which led to the installation of faster operating air cylinders on the A-910, A-920,
and A-940 inline palletizers. The 40-mm bore provided enough force to extend and retract the turner while the
reduced volume and full, open porting enabled fast breakaway and stroke speeds.
Each case turner is a high-speed, vertically mounted guided cylinder with an attached plate that strokes
out and turns oncoming cases on a high-speed conveyor and then stacks them in an intricate pattern on the pallet.
Each case turner uses one cylinder. There are three to four case turners on the palletizers. The stroke
of each cylinder, typically 15 in., engages in a programmed sequence. If one of the cylinders is
too slow, it slows the entire stacking operation.
When FKI Logistex contacted Parker, the company was using a guided cylinder that could not stroke out
the turner timely enough to achieve speed levels required to meet the intricate stacking configuration.
Thus, palletizer-stacking speed was at a maximum of 110 cases per minute – far below the potential of
150 per minute.
Specifications called for the guided cylinder to complete four objectives:
- provide sufficient force to extend and retract the turner, which weighed 20 lbs.
- extend and retract the turner as quickly as possible.
- withstand the kinetic energy produced by cases striking the turner.
- the mounting had to be precisely interchangeable with the company’s current equipment.
Originally, FKI engineers used a 50 mm bore guided cylinder for this application. After analyzing
application requirements, Parker engineers specified a prototype, custom-built P5L 40-mm bore cylinder
with a special housing normally used for a 50-mm cylinder. Appropriate housing modifications were made
to meet dimensional and mounting requirements.
The P5L guided cylinder met all four requirements. The 40-mm bore provided enough force to extend
and retract the turner while the reduced volume and full, open porting enabled fast breakaway and stroke speeds.
The redesigned P5L Series handles most extreme applications and particularly suits those with
compressed design cycles. The cylinders have two case-hardened support shafts directed by four linear
bearings with all components incorporated into a one-piece housing. Bearing options include standard
and oversized composite bushings with chrome plated or stainless steel shafting or self-aligning and
standard recirculating ball bearings with carbon or stainless steel shafting. Composite bushings are
impregnated with Teflon for self-lubrication.
Features include self-aligning bearings for high load capacities; micro-adjusters for high precision,
accurate stroke; direct-mount cylinders to eliminate transition plates; and capacity to control loads of
more than 9000 N while 20-100 mm bores sizes handle strokes in excess of 1500 mm.
The cylinder’s special housing used oversized 35-mm guide rods to absorb the kinetic energy of
moving cases at higher speeds. The custom housing also provided an interchangeable mounting design
that allowed FKI engineers to simply “drop in” the P5L to start running.
FKI engineers tested the new cylinder alongside comparable cylinders, as well as the one used in the
application. “The P5L clearly outperformed alternate cylinders at speeds unmatched by the units we
had been using,” said Dan Ross, FKI Logistex Mechanical Supervisor. “It wasn’t even close.
We were able to increase overall palletizer speed from 110 cases per minute to 150, representing
a production increase of 26%.”
Additional savings accrued from the fact that FKI engineers were not required to design and build their
own high-speed guided cylinders. “For us to do so,” said Ross, “it would have cost $125.00 per unit over
the price of Parker’s P5L cylinders. With an annual average product usage running at 200 units, this
alone saves us $25,000.”
FKI Logistex has chosen the cylinder for all case-turner applications. “As an added bonus,”
Ross continued, “the P5L’s treated guide rods eliminated rod-pitting problems that can occur
from equipment wash-down operations.”
Parker Hannifin Corp.